1G spark issue

redfield102j · Dec 9, 2015

So i started fighting a idle surge issue and very hard to get to start when cold. Had a cel for temp sensor replaiced with a spare i had. No more cel. Car was still very hard to get running when cold and still had idle surge. I went to a leak test next. Found throttle shaft seals where bad. Replaced and have no leaks. Tried to start it and can not get it to even try to start. So i started checking other basics (fuel/spark) fuel is good plenty of pressure and injectors spay great.. went on to spark next and here is where it gets weird to me.. number1 sparks once when first hit key and then sparks erradically meaning once or twice every 30 seconds or more. Numbers 2 and 3 dont spark at all and number 4 is just like 1 but a little more frequently... tested coil and seems fine has new cas new ngk blue wires new plugs new isc new tps and a brand new ecu. I have replaced almost everything on this motor and am getting very frustrated.. any advice or help would be greatly appreciated.. thanks guys

1990TSIAWDTALON · Dec 9, 2015

I can't find the write up on it but check the Power Transistor.

Wait... found this good one from luv2rallye
http://www.dsmtuners.com/threads/how-to-test-the-power-transistors.229419/

redfield102j · Dec 9, 2015

I

1990TSIAWDTALON said:
I can't find the write up on it but check the Power Transistor.

Wait... found this good one from luv2rallye
http://www.dsmtuners.com/threads/how-to-test-the-power-transistors.229419/

just did the haines test on power transistor and on coil. Power transistor checked fine. Coil test were body isulation.. good. Primary resistance on 200 setting is 1.1 on both 1&4 and 2&3.. secondary resistance on 200k setting coil 3/4 12.2 coil 1/2 12.2.... in same order on 20m setting results were both .01.. wasnt sure what setting to use..

mitsubishikid · Dec 9, 2015

inspect the ecu to main engine harness wiring you might have a short somewhere, if all the sensors are reading good wiring would be the next culprit, and check and make sure all your wire connectors are connected and inspect the ends for corrosion or burn marks etc.

Maybe the coil pack suffered heat damage, and will only read bad when warmed up same goes for transistor.

redfield102j · Dec 9, 2015

mitsubishikid said:
inspect the ecu to main engine harness wiring you might have a short somewhere, if all the sensors are reading good wiring would be the next culprit, and check and make sure all your wire connectors are connected and inspect the ends for corrosion or burn marks etc.

Maybe the coil pack suffered heat damage, and will only read bad when warmed up same goes for transistor.

Ok i will start checking wires. I can not warm anything up due to engine will not start at all now. Double checked spark again after coil and pt test and still having same spark issue

o0GuitarKid0o · Dec 9, 2015

The harness for the power transistor is very short

it's possible the pins backed out (on the connector it's self) enough to make the ptu not function properly

Can you do a continuity test ?

Look for breaks by wiggling the wire your testing (one probe on the female ptu connector and the other on the Ecu connector )

Just look for a pin out for your specific Ecu

redfield102j · Dec 9, 2015

o0GuitarKid0o said:
The harness for the power transistor is very short

it's possible the pins backed out (on the connector it's self) enough to make the ptu not function properly

Can you do a continuity test ?

Look for breaks by wiggling the wire your testing (one probe on the female ptu connector and the other on the Ecu connector )

Just look for a pin out for your specific Ecu

I am going to have to make an extention wire to run that test as my leads on tester arent very long. I will definitely check to make sure all wires are pushed into connectors and nothing is goofy

97 eclenger · Dec 9, 2015

how does the ecu itself look?

mitsubishikid · Dec 10, 2015

If you look at the ecu pinouts for your year dsm you can trace where the wires come from on the ecu connector to the sensor connector under the hood, and using an ohm meter you can tell if there is a short, corrosion, or loose pin.
1g http://www.dsmlink.com/images/forums/1GECUPinout.pdf
2g http://www.dsmlink.com/images/forums/2GECUPinout.pdf

redfield102j · Dec 10, 2015

97 eclenger said:
how does the ecu itself look?

The ecu is brand new.

steve · Dec 10, 2015

I haven seen a "brand new" ECU in years and when I did they were $2000. How about a picture of it so I can say I saw one just a while ago?

Most of the "brand new" ECUs around here mean, "brand new to me from some guy who said it was working fine" and turn out to have leaking caps and half rotted circuit boards. Heck most the the "rebuilt" ECUs I've seen were junk done by businesses that didn't care. If it failed and actually came back they had another on the pile to ship out.

redfield102j · Dec 10, 2015

Lol

steve said:
I haven seen a "brand new" ECU in years and when I did they were $2000. How about a picture of it so I can say I saw one just a while ago?

Most of the "brand new" ECUs around here mean, "brand new to me from some guy who said it was working fine" and turn out to have leaking caps and half rotted circuit boards. Heck most the the "rebuilt" ECUs I've seen were junk done by businesses that didn't care. If it failed and actually came back they had another on the pile to ship out.

Thats to funny. I almost bought a ecu from a guy that said that exact thing.. i purchaced mine threw napa. It cost me 340 with a significant friend discount. I believe there list price was somewhere around 560. I can take a pic of it for you if you really want.. i have actually replaced almost all the major components that tell the car what is going on.. this is why i dont understand what is going on.

steve · Dec 11, 2015

redfield102j said:
i have actually replaced almost all the major components that tell the car what is going on.. this is why i dont understand what is going on.

That's why some of us are asking questions you might think are redundant.

I don't know what NAPA is offering but I've seen quite a few ECU's with stickers on them from professional rebuilders that the chains might use and most of them were the worst examples of quick hacks.

I don't propose anybody open up a ECU that has a tamper sticker as long as it still has a warranty but I also don't recommend that just because a part came from a major parts chain that you can assume it's perfect. Just look at how many alternators turn out to be junk.

redfield102j · Dec 11, 2015

steve said:
That's why some of us are asking questions you might think are redundant.

I don't know what NAPA is offering but I've seen quite a few ECU's with stickers on them from professional rebuilders that the chains might use and most of them were the worst examples of quick hacks.

I don't propose anybody open up a ECU that has a tamper sticker as long as it still has a warranty but I also don't recommend that just because a part came from a major parts chain that you can assume it's perfect. Just look at how many alternators turn out to be junk.

I completly understand. I dont mind answering any questions that may or may not help me figure this out. I have always wanted one of these cars. I got very lucky and picked this car up for 300 dollars after it sat in a guys garage for over 10 years with the trans out for clutch replacement. It came with a bunch of extra stuff. I have put over 1500 in parts trying to make this car drivable. It seems that everytime i find an issue and fix it something else is wrong. The car hasnt had more than 50 miles put on it since i bought it. Its starting to drive me crazy. How do i tell if the ecu has issues if there is no cel and i shouldnt take it apart? Is there any pics or info anyone may need to help in the diagnosis? Everyone keeps telling me to take it to a garage and let them deal with it. The problem with that is why pay someone to do what i can.. just need alil help being i am new to these cars

luv2rallye · Dec 11, 2015

Coil's resistance being ok does not guarantee it's good. In fact yours is already weak testing at 1.1 ohms when the spec is 0.77-0.95 ohms. A visual of the spark itself to see it's strength is the best test when you suspect a weak spark. To test the coil by itself for spark see: http://www.dsmtuners.com/threads/is-this-a-ground-no-spark-issues.415723/#post-152745735. This link is for a 2g. For a 1g use the yellow-black for plugs 2 & 3 and yellow-green for plugs 1 & 4.

redfield102j · Dec 14, 2015

So i have been working on the car trying to figure it out. I got good spark to plugs 1 and 4 now with a few random sparks on 2 and 3. Just from rolling the motor over a bunch of times.I should mention while rolling motor over working on spark i got a cel for the cas. So i did the haynes manual test and got low readings on all the viltage tests. Figured due to low battery. So i charged it over night. Came out and redid tha cas test. Results are supply voltage 13.17... signal voltage 3.72.. haines manual says supply voltage should be around 12 and signal voltage should be 4.8 to 5.2.. any ideas on what would cause this?

steve · Dec 14, 2015

The ECU provides the 5v voltage bias to the CAS on the two signal lines. The CAS then pulls them down to ground to signal the blade moving past the sensor.

Unplug the CAS and check the voltages on the two pins again. If it's still low then you either have a short in the CAS wiring or the ECU has a problem. If the voltages are now good, make sure you weren't measuring while the CAS was moving which would cause your meter to average the voltage. If they still are low then the CAS would be suspect.

redfield102j · Dec 14, 2015

The cas was unpluged when i did the test. I unhooked the battery for a few min and hooked it back up. Tried starting the car again. After a couple tries it started and ran for about 3 to 5 min. It seemed to be running ok a few misses here and there but cleaned up as engine warmed. While running i got a cel for the cas again and the car died short time after. I did the viltage test again and it reads 13.12.. and 3.73 on both pins with cas unpluged

redfield102j · Dec 14, 2015

If i was going to check the signal voltage for the cas at the ecu. Wich pin would i be checking? The diagram i found does not really tell me.

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luv2rallye · Dec 14, 2015

ECU pins 21 & 22 are the CAS signals.

redfield102j · Dec 14, 2015

luv2rallye said:
ECU pins 21 & 22 are the CAS signals.

Ok thanks. Now i kook at the pic i see it. Not sure how i missed it..

redfield102j · Dec 15, 2015

Ok i went out and worked in the car today. I tried to start it just to see and it started right up. The idle surge seems to be gone. Does have a miss when running. After engine warms i get a cel. Shut car off and checked the codes. There were none. So i went to checking the cas voltage at the ecu. It is also only 3.17 to both pins.. what does this mean? Is there a relay or anything that could cause faulty voltage to the ecu or is it a i got a bumb ecu when i replaced it? Any ideas or info is greatly appreciated

o0GuitarKid0o · Dec 15, 2015

Best bet would be remove the Ecu open it up and check for shorts on the circuit board with a continuity tester or visually.

You need to double check the wiring again from the cas to the Ecu

It's possible you have a brake in that wire somewhere in the engine bay,
the wires are exposed to the elements and constant heat cycles so it's a possibility

Good luck !
And there's no relay ,Steve explain that the Ecu provides the signal just reread his post

steve · Dec 15, 2015

How are you checking the CAS voltages?

Not seeing a fault code after turning the car off raises some additional questions. There should have been a code stored unless the backup power isn't on.

redfield102j · Dec 15, 2015

steve said:
How are you checking the CAS voltages?

Not seeing a fault code after turning the car off raises some additional questions. There should have been a code stored unless the backup power isn't on.

First check was done at conector exact way haines manual says. The last test was done directly at ecu plug. Both done on the 12v setting on my digital meter. I guess i dont know what the cel was while it was running because it had no codes when i checked it. I will try it again tomorrow and see if cel comes back and will check it while its on to verify what code it is

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